Method of dressing hides



all

UNITED stares rarest OFFICE.

EMIL nearer, or? AGRAM, HUNGARY, Assronon. BY MnsNn ASSIGNMENTS, TO THE CHEMICAL FOUNDATION, INK,

A CORPORATION OF DELAWARE.

METHOD 033 DRESSING HIDES.

No Drawing. Application filed .Tune 28,

To all whom it may concern:

Be it known that I, EMIL Kannr, a subject oi the Emperor of Austria, King of Hungary, residing at Agram, Hungary, have invented a certain new and useful ltlethod of Dressing Hides, of which the following is a full, clear, and exact specification.

My invention relates to a method of dressing hides by means of hydrolytically split tanning-solutions.

it is well known. that through the appli cation of heat several salts precipitate from their aqueous, hydrolytically split solutions, basic heavy soluble salts hydroxide and OX ids. The presence of an electrolyte will stabilise the colloidal solution of the tan ning agent.

Such salts have tanning qualities which in acidic solutions act more slowly than in basic ones, as far as they have tanning qualities at all.

My invention is based on the tact that so lutions of the same basicity tan more slowly or more weakly at relatively low tempera.- tures, z. e. 0l0 C. I am going to en enipli'ly both of these cases in the tollowing paragraphs of this specification designated by the letters a and I).

a. The results obtained in the tannery by using strong chromic oxid subsalts and by using organic compounds of chromlc OXld at least in diluted solutions are very doubt 'lul, tor such solutions are not stable and hence precipitate chromic OXlCl upon standing, which onid becomes distributed over the surface of the hide and is only very poorly absorbed thereby.

But I have found that it these solutions are cooled, then they remain clear even if they are not used for a long time. In other words, the solutions are stable under these conditions.

Such a cooled solution tans the hide well, slowly and uniformly and thus a strong basic solution or an organic compound of chromic oxid may be employed which makes the leather full and so'lt.

The same good results are obtained Whe using terric salts and aluminum salts, in the same manner.

'With ferric salts another advantage is obtained by my method: It is Well known,

Specification of Letters Patent.

Patented Feb. 1, 1921.

1916. Serial No. 106,524.

that organic substances become betteroxidized by iron-solutions, the higher their temperature is and the more acid has been used.

Heretotore the solutions were generally made basic to a certain degree only, as otherwise ferric hydrate precipitates too readily and retards the tanning operation and the surface of the hide becomes overtanned and hard.

Moreover such a solution oxidizes the fibers of the hide and weakens it.

In contradistinction thereto, if according to my present invention such a solution is allowed to cool off, it will be possible to make it basic to a high degree, wlthout run ning in danger of bad tanning and the libers of the hide is not weakened.

Z). If a solution is acidified to such a degree, that it forms a leather-curing compound at relatively low temperatures, for example at 0l0 (3., and it hereupon the hide is caused to absorb the said solution, then, after subsequent heating, the absorbed solution tans the hide well and quickly.

Example:

According to my present invention I place the hide into a solution of ferric acetate, in which advantageously sodium chlorid or another electrolyte, tor example sodium acetate is CllSSOlVGC. A solution containing from ito 23 Fe O corresponding to a solution having a strength of about one to five per cent. of ferric acetate gives the best results. The hide is left in the tanning liquor tor a sufficient length of time until, according to trial and experience, it has absorbed a sutiicient amount of the tanning liquor, is removed from the solution and placed into a warm (for example from 45 to 50 C.) weak solution of salt, or it may be suspended within a warm room. The tanning-liquor, absorbed by the hide becomes active soon after the hide has been exposed to heat for about a minute. Herealter the hide is stored for a short time during which the ferric oxid becomes chemically combined with the hide substance.

If together with the tannil'igr lflitti'dOll fill ing materials are introduced into the hide tor example flour), then these materials become fixed in the same by the precipitation of the basic radical of the iron acetate.

The tanning of leather by impregnating the same with a solution of a chromium salt and thereafter raising the temperature of the impregnated hides, is a Well known process.

One of the essential features of my method, distinguishing the same from the known methods, is to be seen in the fact that my method is a so-called one bath method, While the methods heretofore known eonstitute a so-called double bath method.

According to the present invention it is possible to use a single tanning salt either separated or several-of such salts together, in both instances, (and at the end of the tanning process). at a reduced temperature, and it is also possible to operate by using at the beginning a relatively low temperatureand subsequently heating.

By this process excellent result can be achieved, if ferric salts predominate and only small portions of chromic oxid or chromic salts are used.

. My invention therefore presents a rapid and cheap tanning method by means of Which an excellent product is obtained.

What I claim is:

1. A method of treating hides which consists in tanning the hides by immersing them into basic solutions of metallic salts in their higher oXid state in the presence of an electrolyte and at a lOW temperature and heating the Wet hide for separating the basic oxids of the salts upon and between EMIL KANET.

\Vitnesses Monrz GELBHUN, AUGUST Fueenn. 

